The immunoglobulin Al (IgA1) proteases are extracellular bacterial proteolytic enzymes whose production has been correlated with virulence in several species of human pathogens, including Neisseria gonorrhoeae. Two distinct types of IgA1 protease are produced by the gonococcus, and the type of protease produced by a given isolate correlates with nutritional auxotype, outer membrane protein I serotype, and production of Dam methylase. This application proposes to characterize the genetics, immunology, and physiology of the gonococcal IgA1 proteases. Genes specifying both type 1 and type 2 enzymes have been cloned into E. coli and will be compared by mutational analysis and by DNA sequencing, with particular emphasis placed on analysis of the enzyme active sites, antigenic sites, and the helper region. The hypothesis that this gene encodes a function critical to the growth and survival of the gonococcus will be tested. Enzyme proteins have been purified and will be used to produce specific monoclonal antibodies, which will be utilized to study the protein structure and secretion of these enzymes. The role of the IgA1 proteases in the physiology of the gonococcus, particularly in the structure of the cell surface, will be examined, using isogenic protease positive and negative strains. Linkage of iga genes to genes encoding nutritional requirements, outer membrane antigens, antibiotic resistance, and Dam methylation will be evaluated by cotransformation and chromosome walk techniques. The effect of IgA1 protease mutations and of specific anti-protease antibodies on the pathogenesis of infections caused by N. gonorrhoeae will be examined in model systems. The objectives of this research are to clarify the role of the IgA1 proteases in gonococcal physiology and virulence and to extend our knowledge of the pathogenesis of gonococcal infection and the genetic control of virulence in this organism.